class Person {
  String name;
  int age;

  Person({required this.name, required this.age}); // 必须传入

  String getName() {
    return "${this.name} --- ${this.age}";
  }
}

void main(List<String> args) {
  Person p = new Person(age: 20, name: '张三');
  print(p.name);
}